Mount for electron discharge devices



March 28, 1939.

N. R. SMRTH MOUNT FOR ELECTRON DISCHARGE DEVICES -Filed Feb. 1, 1934 IINVENTOR NEWLL R .SMI'TH ATTORNEY Patented Mar. 28, 1939 PATENT OFFECEMOUNT FOR ELECTRON DISCHARGE DEVICES Newell R. Smith, Bloomfield, N. J.,assignor to Radio Corporation of America, a corporation of DelawareApplication February 1, 1934, Serial No. 709,267

4 Claims.

My invention relates to improvements in electron discharge devices andmoreparticularly to improved means for firmly and accurately positioningthe electrode mount within the envelope of the tube.

In modern tubes, such as a tube having the dome type bulb or envelope,it is found .desirable to firmly hold the electrode assembly intheenvelope to prevent transverse movement of the mount. To this end thedome or other constricted portion of the tube is utilized to steady theelectrode assembly against transverse vibration and to keep the assemblymore firmly established in position than when the assembly is supportedand steadied only from the stem press. The mount should be steadiedsufiiciently to avoid noises such as clicking which is caused by contactbetween the electrode assembly and the envelope when the tube is jarredor vigorously vibrated. The supporting means should be suflicientlyresilient to avoid stresses and distortion of the mount assembly whichare produced when rigid supporting means are provided for the mountand'the mount is forced into the domeof a bulb slightly smaller than theusual size. Attempts to steady the'mount by metal braces which touch thebulb have not been successful as such braces produce strain checks andcracks in the glass during exhaust at points where the metal touches theglass,

The principal object of my invention is to firmly hold and accuratelyposition the free end of an electrode mount within the bulb of anelectron discharge device by resilient means engaging the interior wallsof the bulb without producing a deleterious efiect on the mount duringassembly or injuring the bulb in any way during exhaust.

The novel features which I believe to be characteristic of my inventionare set forth with particularity in the appended claims, but theinvention will be best understood by reference to the followingdescription taken in connection with the accompanying drawing in which:

Figure 1 is a View in perspective and partly broken away of one form ofan electron discharge device embodying my invention;

Figure 2 is an enlarged horizontal cross-section taken along the line2-2 of Figure 1;

Figure 3 is an enlarged partial vertical section taken along the line3-3 of Figure 2;

Figure 4 Ban enlarged View of a mica spacer made in accordance with myinvention;

Figure 5 is an enlarged View of a portion of the collar of Figure '1showing details of the slot for holding the mica spacer shown in Figure4; and

Figure 6 is an enlarged partial view of the collar with the mica spacerin place.

The electron discharge device shown in Figure 5 1 has the usual base I0on a dome type bulb or envelope I I and a contact cap I2 electricallyconnected to a control grid, not shown, but forming a part of the mountassembly I3. Within the tubular portion or dome of the bulb I I is ashield 10 M in the shape of a fiat bottomed cup having in the bo tom are-entrant shallow recess I5 in which the circular mica spacer I6 fitssnugly, covering a rectangular slot I! in the bottom of the shield I4.At the ends of the slot I6 are up- 15 turned ears I8 which are welded tosupport rods I9 extending from the press of the tube. The upper ends ofthe cathode 20 and of the grid rods 2| extend through the mica spacer,which holds them in alignment in the middle of the slot I1 and 20 spacesthem laterally.

As the bulbs are not all of exactly the same diameter, rigid spacers onthe upper end of the mount to fit snugly in the dome are not entirelysatisfactory. If the spacer is rigid and fits the 25 largest bulb, themounts will be stressed and distorted when a smaller bulb is placed overthe mount assembly, while if the spacer fits the smaller bulbs, it willbeloose in the larger bulbs, and clicking will result.

In accordance with my invention the collar-like or cylindrical portionI4 of the shield I4 is provided with a plurality of slots 22 of theshape shown most clearly in Figure 5, into which the spring mica spacersor fingers 23 are fitted and 35 with which they are interlocked. Themica fingers 23 engage the interior wall of the dome to resilientlyspace the mount within the dome portion of the bulb. The resilient micaspacers are stilt enough to steady the mount, but will not 40 causestresses or distortion of the mount. The mica spacer 23 is shaped asbest shown in. Figure 4. The lower end contacts the wall of the bulb,the upper portion being fitted through the wide portion of the slot 22and then tilted into the po- 5 sition shown most clearly in Figures 3and 6 to interlock with the collar portion I4. The angle assumed by thespacer with respect to the vertical collar portion I4 is determined bythe radius R indicated in Figure 4. The smaller this radius 50 the moreacute the angle between the collar and the spacer. The length andthickness of the spacer determines the flexibility of the spacer.

One specific form of the spacer 23 which I have found satisfactory hasan overall length of 55 about thirty-five thousandths of an inch, theradius R about two tenths of an inch, and its center spaced about seventhousandths of an inch away from. the upper edge of the spacer on thedotted line passing through the center of the spacer, as indicated inFigure 4. The width of the mica spacer at the lower or tongue portion isabout 25 hundredths of an inch and its narrowest dimension at theshoulder about two tenths of an inch. The slot 22 in the collar is aboutfour thousandths of an inch wide, its longer portion about twenty-sixone thousandths of an inch, and its shorter portion about two tenths ofan inch the width of each of the two portions of the slot being equal,that is about two one thousandths of an inch. The bottom of the slot ispreferably located about one eighth of an inch from the top of thecollar, which is conveniently about three tenths of an inch in heightand about nine tenths of an inch in outside diameter, the mica spacermaking an angle of about 20 degrees with the portion l4 collar whenmounted in the tube.

While I show three such fingers it is obvious that two or more thanthree could be used. When the bulb is placed over the mount the fingersare flexed downward slightly and to an extent dependent upon the innerdiameter of the dome of the bulb. These fingers. resiliently center theelectrode assembly firmly and accurately within the envelope and preventclicking in the tube.

While I have indicated the preferred embodiment of my invention of whichI am now aware and have also indicated specific applications for whichmy invention may be employed it will be apparent that my invention isnot limited to the exact forms illustrated or the use indicated, butthat many variations may be made in the particular structure used andthe purpose for which it is employed without departing from the scope ofmy invention as set forth in the appended claims.

What I claim as new is:-

1. An electron discharge device having an envelope provided with atubular portion at one end thereof, a mount comprising an electrodeassembly positioned in the other end of said envelope and provided witha member having a collar-like portion extending within the tubularportion of the envelope said collar-like portion having slots spacedaround its periphery, sheet mica springs interlockingly engaged in saidslots and extending outwardly from said mount at an angle to thelongitudinal axis of the tubular portion of said envelope to facilitatethe insertion of said mount into the envelope of the tube and to engagethe interior wall of the tubular portion of said envelope to resilientlyand firmly position said mount within said envelope.

2. An electron discharge device having an envelope provided with atubular portion at one end thereof, a mount comprising an electrodeassembly in the other end of said envelope and provided with a memberhaving a collar-like portion extending within said tubular portion, saidcollarlike portion having slots spaced around its periphery, sheet micasprings interlockingly engaged in said slots and set at an angle to thelongitudinal axis of the tubular portion of said envelope to facilitatethe insertion of said mount into the envelope of the tube and to engagethe interior wall of the tubular portion of said envelope to resilientlyand firmly position said mount within said envelope.

3. An electron discharge device having an envelope provided with atubular portion, a mount comprising an electrode assembly positionedwithin said envelope, a member on said assembly having a cylindricalportion extending within the tubular portion of said envelope coaxiallytherewith and provided with apertures spaced around its periphery,insulating sheet springs mounted in said apertures and fastened to saidcylindrical portion of said member with one end only of each springangaging the interior wall of the tubular portion of said envelope toresiliently and firmly position to mount in said envelope.

4. An electron discharge device having an envelope provided with atubular portion, a mount comprising an electrode assembly positioned insaid envelope, a member on said assembly having a collar-like portionextending within the tubular portion of said envelope coaxiallytherewith and provided with spaced slots around its periphery, sheetmica springs having inner and outer ends and interlockingly engaged insaid slots the outer end only of each mica spring contacting the innerwall of the tubular portion of the envelope to resiliently and firmlyposition said mount within said envelope.

NEWELL B. SMITH.

